The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted to be prior art against the present disclosure.
This disclosure relates to a method and system for reading data that has been recorded in an arrangement of tracks on a storage medium and is read by a read head that moves relative to the surface of the storage medium. More particularly, this disclosure relates to compensating, during a read operation, for contributions to the read signal from an adjacent track or tracks.
In magnetic recording, as one example of a type of recording in which reading and writing are performed by a head that moves relative to the surface of the storage medium, data may be written in circular tracks on a magnetic disk. In known magnetic recording systems, track pitch is limited by the write head width. The read head is designed to be narrower than the write head so that reading can occur without picking up signals from any adjacent track. In addition, guard bands—empty bands on either side of each track—are provided to help prevent cases where data on one track are overwritten during writing of an adjacent track because of write head positioning errors.
In order to increase recording densities, it is desirable to shrink the track pitch and reduce or remove the guard bands between the tracks, which allows more tracks to fit on the recording medium. For example, in “Shingle Write Recording,” the tracks are written so that one track partially overlaps the previous track. In such a system, track pitch theoretically may be arbitrarily small. In practice, in a Shingle Write Recording system, the track pitch is limited by the read head width. If track pitch is narrower than the read head width, then the read head may pick up a significant amount of signals from one or more adjacent tracks, leading to low data reliability.
In order to further reduce the track pitch beyond the read head width, it is necessary to mitigate the interference picked up from adjacent tracks during a read operation. If the component of the adjacent track picked up by the read head is sufficiently small, it may be possible to use knowledge of the data written on the adjacent track to carry out ITI cancellation.
Copending, commonly-assigned U.S. patent application Ser. No. 12/882,802, filed Sep. 15, 2010 and hereby incorporated by reference herein in its entirety, describes a method and system for compensating for ITI by using actual or estimated data from the adjacent track.